For some strange reason there are a whole bunch of really unhelpful guides on how to increase the size of a virtualbox vdi image. Some of the guides use the resize command which doesnt seem to work anyways.
So here is the procedure to resize the disk:
- Create a new disk of desired size
- Open up command prompt or linux terminal and enter the following command VBoxManage clonehd old.vdi new.vdi –existing
- This will clone the old disk to the new disk
- Go to settings for the virtual machine and remove the old disk and add the new disk
- Boot up
- Right click on my computer and click on manage
- Click on disk management
- Right click on the C drive and click on extend volume
- Follow the prompts, finish, and enjoy your newly resized disk
Cheers!